A couple of things are going on here.
First, the SM57 needs a TON of gain, which is more or less volume boosted before the signal hits the final record point. That's just the way this mic is, no getting around it. It's just not super-sensitive.
Second, you probably have a sound card to which you have to run a little 1/8" input, like a headphone plug, right? And it's probably the stock card that came with the computer. Because it's not designed for this type of recording--and is pretty much unsuitable for any microphone input at all--it has a very high noise floor. The card and not the mic is more than likely the source of the fuzz.
Now as for the noise removal, it's going to be VERY touchy. I've found even higher quality removal plug-ins to be effective only on the noise and not distort the instrumentation at extremely low levels. NR is dangerous. People very often get over-zealous and end up with that nasty, alien landing sounding thing.
Some things that can help the problem.
First, you need something to get you some gain to drown out the noise floor. A mic preamp or a mixer should do this. Here's a link to some single-channel mic pres, any of which should do the job you need.
http://www.sweetwater.com/c662--Single_ ... s/low2high
Two things about those. First you'll need at least one more cable, because they either use XLR (Microphone) or 1/4" (Guitar cable type) inputs, so you need one cable to go Mic>Pre and one to go Pre>Sound card. Both of these cables are easily and cheaply available at any music store.
Second, DO NOT, under any circumstances turn on "Phantom Power" on the mic pre with the SM57. This is a dynamic microphone and does not need and will not handle any sort of electricity being sent to it.
The second thing I'd recommend doing is getting a new sound card, like the M-Audio Audiophile 2496, which has very good analog inputs.
Or, instead of the pre and the card, you can go with a USB or Firewire interface, which will do the job of both in one box. If you have the cash, this is the option I'd recommend, considering it fully bypasses what is likely the noisiest part of your chain and you get everything in one unit, and it's probably more cost-effective. The caveat about Phantom Power still remains. Absolutely make sure it's off as long as you are using this mic.
USB Interfaces:
http://www.sweetwater.com/c695--USB_Aud ... s/low2high
Firewire Interfaces:
http://www.sweetwater.com/c683--FireWir ... s/low2high
Feel free to ask any questions you might have. Good luck.
At this point, the cheaper the better.
